The present invention relates to a toner collecting apparatus for collecting toner remaining on the surface of a photosensitive drum in a copying machine or a facsimile machine.
Conventionally, there is known a toner collecting apparatus for collecting toner remaining on the surface of a photosensitive drum in a copying machine or the like in which toner collected from the surface of the photosensitive drum is conveyed to a predetermined position through a toner discharging case and is let fall spontaneously released in a toner collecting container which is made of transparent plastic and can be mounted on the main body of a copying machine. An optical sensor having a light emitting portion and a light receiving portion located opposite to the light emitting portion is disposed on the toner collecting container as mounted on the main body, the sensor being adapted to detect that the amount of toner collected in the toner collecting container has reached a predetermined amount. Further, a cleaning member is disposed for cleaning those portions of the toner collecting container opposite to the light emitting portion and the light receiving portion, such cleaning being made automatically in association with the mounting of the toner collecting container on the main body of the copying machine at a predetermined position (Japanese Patent Laid-Open Publication No. 116568/1983).
In the toner above-mentioned collecting apparatus, the portions of the toner collecting apparatus between the light emitting portion and the light receiving portion can be cleaned only when the toner collecting container is mounted on the main body of the copying machine at its predetermined position, and cannot be cleaned at all while the toner collecting operation is carried out.
While the toner collecting operation is carried out, toner falls spontaneously. Therefore, when toner reaches the lowest portion of the toner collecting container, the toner scatters as a reaction and such scattering toner sticks to the inner surface of the transparent toner collecting container.
Therefore, even though the toner collecting container was cleaned at the time the toner collecting container was mounted on the main body of the copying machine, the toner collecting container to which toner sticks afterward cannot be cleaned. Accordingly, even through the amount of toner collected is still relatively small, the light passage between the light emitting portion and the light receiving portion may be obstructed by scattering or sticking toner so that the optical sensor may erroneously judge that the amount of toner collected has reached a predetermined amount.
Conventionally, there is known another toner collecting apparatus in which a photosensitive drum and a toner collecting container for housing toner collected from the photosensitive drum are formed in a unitary construction which can be used as an expandable unit (Japanese Patent Laid-Open Publication No. 154255/1982).
In the expendable unit above-mentioned, the photo-sensitive drum and the toner collecting container are integrally mounted on an arm and removably attached to the main body of a copying machine. The total amount of toner collected when the photosensitive drum has been used as much as the liftime number of rotations of the photosensitive drum is calculated. The volume of the toner collecting container is set such that the toner collecting container can house the toner amount thus calculated. Therefore, when the number of actual rotations of the photosensitive drum reaches its lifetime number of rotations above-mentioned, the expendable unit is to be replaced.
However, the amount of toner remaining on the surface of the photosensitive drum after the photosensitive drum is used one, varies with various conditions such as the contents or size of an original document, a preset copying density, a temperature, a charged amount of the photosensitive drum which is electrified due to ambient humidity, and the amount of transferred toner. Therefore, even though the number or actual rotations of the photosensitive drum has reached its lifetime number of rotations, the total amount of toner actually collected may be significantly different from the calculated amount of toner above-mentioned.
If the amount of toner actually collected is greater than the calculated amount of toner to be collected, the toner collecting container is almost filled up with collected toner, even though the number of actual rotations of the photosensitive drum does not reach its lifetime number of rotations. Therefore, the toner collecting container has no more space for housing collected toner and the collected toner disadvantageously overflows from the toner collecting container. Since a relatively less expensive toner collecting container cannot be used, it becomes necessary to replace the expendable unit with a new one even though an expensive photosensitive drum might still be fit for use. This means that an expendable unit which might still be fit for use, is discarded and the cost to be borne by the user is increased.
Conventionally, there is known a further toner collecting apparatus in which a toner collecting container is disposed adjacent the photosensitive drum and a screw conveyor or the like for conveying toner is used (Japanese Utility Model Laid-Open Publication No. 178169/1983).
Such toner collecting apparatus includes a cleaning blade for scraping away toner remaining on the surface of the photosensitive drum, and a seal blade for receiving toner scraped away by the cleaning blade, the seal blade located under and opposite to the cleaning blade. This toner collecting apparatus further includes a rotatable toner scraping plate or a toner discharging belt so that this plate or belt comes in contact with the top surface of the seal blade, and a toner collecting container downstream of the toner scraping plate or the toner discharging belt.
In this toner collecting apparatus, toner scraped away by the cleaning blade can be guided to the toner collecting container adjacent the photosensitive drum. Such arrangement shortens the toner conveying distance, thereby to enable to significantly reduce a stain inside of the main body of a copying machine by toner.
In this toner collecting apparatus, however, toner is merely moved toward the toner collecting container by the toner scraping plate or the toner discharging belt. Therefore, toner can be actually housed in the toner collecting container only at its area lower than the toner scraping plate or the toner discharging belt. Therefore, the amount of toner to be collected is disadvantageously reduced.
A strong demand for a smaller-size copying machine, a facsimile machine or the like has increased. In order to satisfy such demand, a passage for conveying copying paper is disposed as close to the lower surface of the photosensitive drum as possible. It is therefore required that the height of the toner collecting container to be disposed adjacent the photosensitive drum, in particular the bottom of the toner collecting container, does not interfere the paper conveying passage. Further, in order to let toner scraped by the cleaning blade effectively fall onto the seal blade and to prevent the falling toner from staying thereon, the toner scraping plate or the toner discharging belt is located in a position which is separted by a predetermined distance from the photosensitive drum and opposite to the substantially center part thereof. Therefore, the volume of the area of the toner collecting container lower than the toner scraping plate or the toner discharging belt is inevitably reduced to accordingly reduce the amount of toner to be collected.
Conventionally, the seal blade for receiving toner scraped away from the surface of the photosensitive drum is securely bonded to a blade holder and is attached to the lower wall of a toner receiving port of the toner collecting container with setscrews through a pressing members having slots such that the contact pressure and the distance between the tip of the seal blade and the photosensitive drum can be adjusted.
In transporting a copying machine or the like having such seal blade as above-mentioned, if the seal blade is in contact with the photosensitive layer of the photosensitive drum at the same position for a long period of time, external vibration may provoke cracks in the photosensitive layer of the photosensitive drum and the tip of the seal blade may be deformed. This may reduce the quality of a copied image and produce a gap between the seal blade and the surface of the photosensitive drum. Therefore, toner scraped away from the photosensitive drum disadvantageously comes out to the outside of the toner collecting container.
At the time of transport of toner collecting apparatus having such a conventional seal blade, the setscrews are once loosened and the seal blade together with the blade holder is moved along the slots of the pressing members, and the setscrews are then tightened to fit the seal blade such that the seal blade is kept away from the photosensitive drum. In use of this toner collecting apparatus, the seal blade together with the blade holder is moved up to the predetermined position so that the tip of the seal blade comes in contact with the photosensitive layer of the photosensitive drum.
In such conventional toner collecting apparatus, however, it is required to rotate the setscrews in order to move the seal blade to a predetermined position such that the tip of the seal blade comes in contact with the photosensitive layer of the photosensitive drum or is kept away from the photosensitive drum. This disadvantageously requires much labor of mounting works. Further, if the seal blade is set at a predetermined position with the setscrews tightened insufficiently, the seal blade will be gradually moved together with the blade holder, so that the tip of the seal blade is separated from the surface of the photosensitive drum. This may introduce the problem that toner scraped away from the photosensitive drum falls outside of the toner collecting container.
Further, in a transfer device for transferring to copying paper a toner image formed on the photosensitive drum, there are instances where copying paper to which the toner image has been transferred is not separated from the photosensitive drum by a separating device and enters the toner collecting apparatus along the photosensitive drum. In such case, the rotation of the photosensitive drum causes the tip of the copying paper to come in contact with the lower end of the cleaning blade, so that the copying paper is bent. The bend causes the tip of the seal blade to be pushed to the toner feeding member for conveying toner to the toner collecting container. The seal blade is therefore deformed. At this time, the toner feeding member is rotated in the same direction to the rotating direction of the photosensitive drum. The tip of the seal blade is therefore rolled in the toner feeding member and extremely bent. The seal blade once rolled in and deformed by the toner feeding member cannot be perfectly restored as to contact pressure to the surface of the photosensitive drum even though the deformed portion is repaired. Therefore, such deformed seal blade cannot be used.